/*

* Copyright (C) 2001-2005, International Business Machines Corporation and others. All Rights Reserved.

**********************************************************************

*   Date        Name        Description

*   07/18/01    aliu        Creation.

**********************************************************************

*/

#ifndef UNIMATCH_H

#define UNIMATCH_H

#include "unicode/utypes.h"

/**

 * \file 

 * \brief C++ API: Unicode Matcher

 */

U_NAMESPACE_BEGIN

class Replaceable;

class UnicodeString;

class UnicodeSet;

/**

 * Constants returned by <code>UnicodeMatcher::matches()</code>

 * indicating the degree of match.

 * @stable ICU 2.4

 */

enum UMatchDegree {

    /**

     * Constant returned by <code>matches()</code> indicating a

     * mismatch between the text and this matcher.  The text contains

     * a character which does not match, or the text does not contain

     * all desired characters for a non-incremental match.

     * @stable ICU 2.4

     */

    U_MISMATCH,

    /**

     * Constant returned by <code>matches()</code> indicating a

     * partial match between the text and this matcher.  This value is

     * only returned for incremental match operations.  All characters

     * of the text match, but more characters are required for a

     * complete match.  Alternatively, for variable-length matchers,

     * all characters of the text match, and if more characters were

     * supplied at limit, they might also match.

     * @stable ICU 2.4

     */

    U_PARTIAL_MATCH,

    /**

     * Constant returned by <code>matches()</code> indicating a

     * complete match between the text and this matcher.  For an

     * incremental variable-length match, this value is returned if

     * the given text matches, and it is known that additional

     * characters would not alter the extent of the match.

     * @stable ICU 2.4

     */

    U_MATCH

};

/**

 * <code>UnicodeMatcher</code> defines a protocol for objects that can

 * match a range of characters in a Replaceable string.

 * @stable ICU 2.4

 */

class U_COMMON_API UnicodeMatcher /* not : public UObject because this is an interface/mixin class */ {

public:

    /**

     * Destructor.

     * @stable ICU 2.4

     */

    virtual ~UnicodeMatcher();

    /**

     * Return a UMatchDegree value indicating the degree of match for

     * the given text at the given offset.  Zero, one, or more

     * characters may be matched.

     *

     * Matching in the forward direction is indicated by limit >

     * offset.  Characters from offset forwards to limit-1 will be

     * considered for matching.

     * 

     * Matching in the reverse direction is indicated by limit <

     * offset.  Characters from offset backwards to limit+1 will be

     * considered for matching.

     *

     * If limit == offset then the only match possible is a zero

     * character match (which subclasses may implement if desired).

     *

     * As a side effect, advance the offset parameter to the limit of

     * the matched substring.  In the forward direction, this will be

     * the index of the last matched character plus one.  In the

     * reverse direction, this will be the index of the last matched

     * character minus one.

     *

     * <p>Note:  This method is not const because some classes may

     * modify their state as the result of a match.

     *

     * @param text the text to be matched

     * @param offset on input, the index into text at which to begin

     * matching.  On output, the limit of the matched text.  The

     * number of matched characters is the output value of offset

     * minus the input value.  Offset should always point to the

     * HIGH SURROGATE (leading code unit) of a pair of surrogates,

     * both on entry and upon return.

     * @param limit the limit index of text to be matched.  Greater

     * than offset for a forward direction match, less than offset for

     * a backward direction match.  The last character to be

     * considered for matching will be text.charAt(limit-1) in the

     * forward direction or text.charAt(limit+1) in the backward

     * direction.

     * @param incremental if TRUE, then assume further characters may

     * be inserted at limit and check for partial matching.  Otherwise

     * assume the text as given is complete.

     * @return a match degree value indicating a full match, a partial

     * match, or a mismatch.  If incremental is FALSE then

     * U_PARTIAL_MATCH should never be returned.

     * @stable ICU 2.4

     */

    virtual UMatchDegree matches(const Replaceable& text,

                                 int32_t& offset,

                                 int32_t limit,

                                 UBool incremental) = 0;

    /**

     * Returns a string representation of this matcher.  If the result of

     * calling this function is passed to the appropriate parser, it

     * will produce another matcher that is equal to this one.

     * @param result the string to receive the pattern.  Previous

     * contents will be deleted.

     * @param escapeUnprintable if TRUE then convert unprintable

     * character to their hex escape representations, \\uxxxx or

     * \\Uxxxxxxxx.  Unprintable characters are those other than

     * U+000A, U+0020..U+007E.

     * @stable ICU 2.4

     */

    virtual UnicodeString& toPattern(UnicodeString& result,

                                     UBool escapeUnprintable = FALSE) const = 0;

    /**

     * Returns TRUE if this matcher will match a character c, where c

     * & 0xFF == v, at offset, in the forward direction (with limit >

     * offset).  This is used by <tt>RuleBasedTransliterator</tt> for

     * indexing.

     * @stable ICU 2.4

     */

    virtual UBool matchesIndexValue(uint8_t v) const = 0;

    /**

     * Union the set of all characters that may be matched by this object

     * into the given set.

     * @param toUnionTo the set into which to union the source characters

     * @stable ICU 2.4

     */

    virtual void addMatchSetTo(UnicodeSet& toUnionTo) const = 0;

};

U_NAMESPACE_END

#endif